Fluorescent quantitative polymerase chain reaction (qPCR) is a DNA amplification technology improved in multiple aspects based on a polymerase chain reaction (PCR). When the qPCR is performed in a thermal cycler instrument, the instrument illuminates each DNA sample by emitting light beams of special wavelengths and detects and excites fluorescence emitted by fluorophonre. qPCR needs to use a fluorescent probe or fluorescent primers, and the variation quantity of target DNA can be monitored by a real-time PCR instrument during instant amplification. In addition, the qPCR is further capable of simultaneously amplifying one or more target DNA sequences.
The quantitative PCR has strict requirements for DNA templates, and can be performed by purifying pure DNA from biological samples generally. The conventional complicated DNA extraction methods are mainly as follows: (1) a classical conventional phenol/chloroform DNA extraction method is time-consuming, complicated in extraction steps and high in toxicity and cannot be used for a high-throughput experiment. In addition, chemical phenol/chloroform reagents have been demonstrated to be important cancerogenic substances in labs, being able to cause irreversible injuries to the body of an operator due to long-term exposure and may form a large threat to health and safety; (2) in an ion exchange spin column method, DNA is collected by a silica membrane, the multi-steps are relatively complicated, a centrifugal machine needs to be repeatedly used, centrifuge tubes are repeatedly replaced, DNA contamination among samples may occur, DNA is easily lost in the experimental process, the extraction amount is small, the price is high, and lab wastes which are difficult to eliminate may be produced. The above two methods are not favorable for the high-throughput experiment; and (3) a magnet bead method (also known as a glass bead separation method): the method for purifying DNA by using magnet beads is relatively simple and convenient, and the frequency of replacing the centrifuge tubes is relatively low, while multiple steps are needed, and a high-value expensive special equipment of an automatic workstation is needed. The automatic workstation adopted in the DNA purification method by magnet beads is very typical high-value equipment. DNA is also partially lost in the experimental process. In addition, although the frequency of replacing the centrifuge tubes is relatively low in the DNA separation method by magnet beads, multiple steps are needed, and expensive special equipment is needed. In these existing technologies, the centrifuge tubes need to be repeatedly replaced or the DNA needs to be repeatedly cleaned and collected, thereby easily causing cross contamination of samples. There is limited report about methods for directly performing real-time quantitative PCR without DNA extraction, especially for use of many kinds of samples. Therefore, the provision of a lytic composition which can be directly used for nucleic acid analysis without nucleic acid purification, a kit, a method for preparing nucleic acid by utilizing the lytic composition and a nucleic acid analysis method has great practical significances.